The creeping animals that the waters breed symbolize facts that the outer self knows. Birds in general symbolize logical reasoning; they also symbolize matters that we truly understand, which belong to the inner self.
The following verses in Isaiah demonstrate the symbolism of the creeping animals of the waters—fish—as facts:
I came and there was no man. In my censure I will dry up the sea; I will make the rivers a desert; their fish will stink from lack of water and die of thirst; I will dress the heavens in black. (Isaiah 50:2, 3)
Evidence still clearer appears in Ezekiel, where the Lord describes a new temple, the general meaning of which is a new church and an adherent of the church or person reborn (since everyone who is reborn is a temple to the Lord).
The Lord Jehovah said to me, “That water, which will go out to the boundary toward the east and go toward the sea, will be channeled down into the sea, and the water [of the sea] will be cured. And it will come about that every living soul that creeps out in any place where the water of the rivers goes will survive; and the fish will be very numerous, because that water goes there and will be cured, and everything will live, wherever the river goes. And it will happen that the fishers will stand over it from En-gedi to En-eglaim; they will be there spreading their nets. Their fish will be of all kinds, like the fish of the great sea, very numerous.” (Ezekiel 47:8, 9, 10)
“Fishers from En-gedi to En-eglaim spreading their nets” symbolize people who are to teach the earthly plane of the human mind about the truths that make up faith.
Passages in the prophets establish the fact that birds symbolize logical reasoning and concepts truly understood. In Isaiah, for example:
I am calling the winged creature from the sunrise, the man I planned on, from a faraway land. (Isaiah 46:11)
I looked and there, not a human! And every bird of the heavens had fled. (Jeremiah 4:25)
I will plant a cutting of the tall cedar, and it will lift its branch and make fruit and become a majestic cedar. And every bird of every wing will live under it; in the shade of its branches they will live. (Ezekiel 17:[22,] 23)
And in Hosea, where the subject is a new church, or the regenerate person:
And I will strike a pact with them on that day—with the wild animal of the field, and with the bird in the heavens and the creature that moves on the ground. (Hosea 2:18)
The wild animal obviously does not mean a wild animal or the bird a bird, because the Lord is sealing a new pact with them.
Nothing that is a person’s very own has any life in it. When presented to view, it looks hard as bone, and black. Everything that comes from the Lord, on the other hand, has life. It has a spiritual and heavenly quality and looks like something living and human.
Incredibly, perhaps (although it is absolutely true), each word, each mental image, and each scintilla of thought in an angelic spirit is alive. Passion received from the Lord, who is life itself, permeates every single thing about such a spirit.
Things that come from the Lord, then, contain life because they contain faith in him, and they are symbolized here by a living soul. Additionally, they have the equivalent of a physical body, symbolized by that which moves or creeps. This information remains obscure to the human mind, but since the verse talks about a living soul that moves, I need at least to mention it.
from Secrets of Heaven, Volume 1, Sections 40-41